BLOOD-GLOBULES. 



217 



Fig. 58. 



BLOOD-GLOBULES, swollei 

 water. 



by the imbibition of 



edges of the globules, being thicker than the central portions, and 

 absorbing water more abundantly, become turgid, and encroach 

 gradually upon the central 

 part. (Fig. 58.) It is very 

 common to see the central 

 depression under these cir- 

 cumstances, disappear on one 

 side before it is lost on the 

 other, so that the globule, as 

 it swells up, curls over to- 

 wards one side, and assumes 

 a peculiar cup-shaped form 

 (a). This form may often be 

 seen in blood-globules that 

 have been soaking for some 

 time in the urine, or in any 

 other animal fluid of a less 

 density than the plasma of 

 the blood. Dilute acetic acid 



dissolves the blood-globules more promptly than water, and solu- 

 tions of the caustic alkalies more promptly still. 



If a drop of blood be allowed partially to evaporate while under 

 the microscope, the globules 

 near the edges of the prepa- 

 ration often diminish in size, 

 and at the same time present 

 a shrunken and crenated ap- 

 pearance, as if minute gran- 

 ules were projecting from 

 their surfaces (Fig. 59); an 

 effect apparently produced 

 by the evaporation of part 

 of their watery ingredients. 

 For some unexplained rea- 

 son, however, a similar dis- 

 tortion is often -produced in 

 some of the globules by the 

 addition of certain other ani- 

 mal fluids, as for example the 

 saliva; and a few can even be seen in this condition after the 

 addition of pure water. 



Fig. 59. 



BLOOD-GLOBULES, shrunken, with their margins 

 crenated. 



